var loadingStyle = `
/**
  * sync loading
  **/
.lds-dual-ring {
  display: inline-block;
}
.lds-dual-ring:after {
  content: " ";
  display: block;
  width: 4px;
  height: 4px;
  margin: 4px;
  border-radius: 50%;
  border: 6px solid #cef;
  border-color: #cef transparent #cef transparent;
  animation: lds-dual-ring 1.2s linear infinite;
}
@keyframes lds-dual-ring {
  0% {
    transform: rotate(0deg);
  }
  100% {
    transform: rotate(360deg);
  }
}
`;
jQuery('head').append('<style>{style}</style>'.replace('{style}', loadingStyle));
var loadingDiv = '<div id="sync-loading" class="lds-dual-ring"></div>';